Electric timepiece



Jan. 14, 1969 G. RAVAL ELECTRIC TIMEPIECE Sheet Filed July 5. 1966 INVENTOR Gaskon Raval BYCgZM G. RAVAL Sheet INVENTOR Gaston Raval BY & 1,4

ELECTRIC TIMEPIECE fi Na 5 3 Jan. 14, 1969 Filed July 5, 1966 United States Patent 9,603/65 US. Cl. s-s5.s 11 Claims Int. Cl. G04c 5/00 ABSTRACT OF THE DISCLOSURE An electric timepiece comprising a resonator and means for electrically sustaining oscillation of this resonator, wherein the hands are driven by pawl means engaging a ratchet-wheel, said pawl means being disengageable for hand setting of the timepiece.

This invention relates to an electric timepiece comprising a resonator and means for electrically sustaining oscillation of this renoator, a pawl coupled with said resonator and engaging a ratchet-wheel, a stop pawl for said ratchet wheel and means for disengaging said pawls from the ratchet-wheel.

In a prior timepiece of this type a mechanism operable by the winding shaft and having pins adapted to lift springs carrying said pawls has been used for disengage ment of said pawls. \However, this prior device has a number of disadvantages. It is evident that the disengaging pins have to be disposed between the ratchet-wheel and said springs of said pawls. The space available between these elements is usually extremely limited. It is thus necessary to use pins of extremely small dimensions and the displacement of such pins has to be limited very accurately in each direction.

Accurate limitation of the pin displacement is further required in order to prevent excessive bending and deformation of the pawl springs by excessive disengaging movement of the pins. -In order to provide sufficient space for the pawl springs and the disengaging pins it may be necessary to bend the springs.

It must be considered that oscillation of the driving pawl usually continues when it is disengaged from the ratchet-wheel. In the above prior mechanism substantial friction occurs between the -pawl spring and the disengaging pin supporting it. By this friction the oscillation of the resonator is attenuated and affected and the pawl spring and disengaging pin are worn.

For practical reasons the members supporting said disengaging pins must be arranged below the pawl springs. :It is thus impossible to remove the disengaging mechanism for the pawls without first removing the pawls.

This invention aims in overcoming the disadvantages of the above prior mechanism. The timepiece according to this invention is broadly characterized in that said means for disengaging the pawls comprise at least one magnet adapted to disengage said pawls by magnetic attraction. The magnet or magnets for disengaging the pawls by magnetic attraction may be disposed outside the pawls where the available space is less limited. A single magnet may be used for disengagement of both pawls whereby the disengaging mechanism may be simplified. Since the pawl springs are attracted by the magnet or magnets and automatically leave the magnet when the latter is retired to its inoperative position, only the operating position of the magnet or magnets, for which the pawls are attracted must be determined and limited with some accuracy. The pawl springs are attracted against the magnet or magnets 3,421,312 Patented Jan. 14, 1969 by a magnetic force slightly exceeding the force of the springs so that the pressure of the springs against the magnet and consequently friction between such elements is relatively low and is determined by the difference of the above forces. Moreover, since the ratio between the magnetic force in the direction of magnetisation of the magnet and the force in the transversal direction is very high, the frictional froce in transversal direction is accordingly low.

One embodiment of the invention is illustrated by way of example in the attached drawing, wherein FIG. 1 is a top view of the disengaging mechanism in its rest position,

FIG. 2 is a top view of the disengaging mechanism in its operative position,

FIG. 3 is a section along line III-III in FIG. 1 and FIG. 4 is a section along line IVIV in FIG. 1.

The timepiece comprises a ratchet-wheel 1 mounted on the shaft '2 of the second wheel. In fact the ratchetwheel 1 replaces the second wheel of usual mechanical timepieces. FIG. 3 also shows the center-wheel 3 and the hour wheel 4 driven from the shaft 2 by wheels not shown in the drawing.

Usually a driving pawl 5 and a stop pawl 6 engage the toothing of the ratchet-wheel 1, such pawls being mounted on leaf springs 7 and 8 respectively. The spring 7 of the driving pawl 5 is fixed at the one end of an arm 9 of a lever 10 mounted on a pivot pin 11. The fork 12 of the lever 10 may be oscillated by an eccentric member mounted on the shaft of the balance wheel not shown.

'The pawl spring 8 is fixed in a stud 13 pressed into a sliding stud 14. The sliding stud .14 has an elongated recess 15 with inclined surfaces 16 (FIG. 4). Two adjusting screws 17 engage the inclined surfaces 16 of the sliding stud. By displacement of the screws in opposite direction the sliding stud 14 may be displaced in lonitudin-al direction for fine adjustment of the position of the stop pawl 6.

The free ends of the pawl springs 7 and 8 are disposed substantially in a common plane near a permanent mag-- net 19 of cylindrical form arranged between two lpolo pieces 20 and 21 of soft iron. The magnet 19 and the pole pieces 20 and 21 are fixed on a lever 22 mountedon a pivot pin 23. The lever 22 has a stud 24 loaded by the one end of a spring 25 whereby the lever 22 tends to rotate in clockwise direction round its pivot pin 23. In the rest position of the mechanism shown in FIG. 1 a surface 26 of the lever 22 engages a stud 27 fixed in a two-armed lever 28. The lever 28 is mounted on a pivot pin 29. A stud 30 of the lever 28 engages into a slit or fork 31 of a locking slide 32. The operating positions of the locking slide 32 are determined by engagement of its nose 33 into notches .34 and 35 respectively of a locking spring 36. The locking slide is mounted on a pivot .pin 37. A Stud 38 of the locking slide 32 engages into an annular groove 39 of the winding shaft 40.

The winding shaft 40 has a thin and flexible portion 41 carrying at its inner end a cylindrical member 42 of larger diameter and a cylinder or mantle 43 of soft resilient material such as rubber or plastics. The centerwheel 3 has an annular clot 44. The lever 28 has a lower arm 45 with an inclined actuating surface 46 at its free end. In the rest position of the mechanism the winding shaft 40 is in its inner end position and the arm 45 of lever 28 supports the portion 42 of the winding shaft in such a position that the cylinder 43 of resilient material is disengaged from the clot 44 and the flexible portion 41 of the winding shaft 40 is bent upwardly as shown in FIG. 3.

Operation of the timepiece is as follows:

As set out above the driving pawl 5 is usually oscillated 3 from the balance wheel (not shown) through the fork 12, the lever 10, the arm 9 and the pawl spring 7. The ratchetwheel 1 is advanced by the pawl and the stop pawl 6 avoids backward rotation of the ratchet-wheel. In the embodiment illustrated by way of example the balance wheel oscillates at a frequency of five c.p.s. and the ratchet-wheel 1 has 300 teeth and consequently is rotated once in a minute. For hand-setting of the timepiece the winding shaft 40 is pulled at the right. The locking slide 32 is thereby rotated in anticlockwise direction and the outer end position of the winding shaft is determined by the position of the winding shaft when the nose 33 of the latter engages the notch 35 of the locking spring 36.

, Due to the above rocking movement of the locking slide 32 the lever 28 is turned in clockwise direction. The arm 45 of lever 28 is thus retracted from portion 43 of the winding shaft and the inner end of the latter is displaced downwardly by the spring action of the bent portion 41. The cylinder 43 of resilient material is thus pressed against the clot 44 of the center-wheel 3 and a friction transmission is established between the winding shaft 40- and the center-wheel 3.

When the lever 28 is displaced in clockwise direction as mentioned above, the stud 27 of this lever allows rotation of the lever 22 in clockwise direction under the action of spring 25. This displacement of the lever 22 is limited by a stud 47. The elements of the mechanism are thus brought into the position shown in FIG. 2. For this position the magnetic fields set up in the air gaps formed between the magnet 19 and the pole pieces 20 and Marc able to attract the pawl springs into the position shown in FIG. 2, wherein the pawls 5 and 6 are disengaged from the toothing of the ratchet-wheel 1. The time-piece may now be set by rotation of the winding shaft, whereby the ratchet-wheel 1 is free to rotate in any desired sense. The second hand may thereby be continuously driven by the hand-setting movement of the timepiece, because pawls 5 and 6 are disengaged.

When the timepiece has been set, the Winding shaft 40 is pressed into its inner end position shown in FIGS. 1 and 3. The locking slide 32 and the lever 28 are returned to the initial positions shown in FIG. 1. The arm 45 of the lever 28 lifts the portion 42 of the winding shaft by engagement of its inclined surface 46 below the portion 42. The stud 27 of lever 28 engages the surface 26 of lever 22 which is thus returned into its rest position illustrated in FIG. 1. When the magnet 19 and the pole pieces 20 and 21 are displaced towards the right from the position shown in FIG. 2, the increasing force of the pawl springs 7 and 8 soon exceeds the magnetic attraction acting onto such springs and the pawls 5 and 6 are returned into engagement with the ratchet-wheel 1. The driving pawl 5 now continues to advance the ratchet-wheel 1.

Of course another disposition of the various elements of the mechanism is feasible. A separate magnet may be associated to each of the pawl springs 7 and 8 respectively. Instead of a winding shaft having a flexible portion a usual winding shaft and the wheels of the timepiece for handdisengageable coupling may be provided between the setting.

What is claimed:

1. An electrical timepiece comprising a resonator and means for electrically sustaining oscillation of this resonator, a pawl coupled with said resonator and engaging a ratchet-Wheel, a stop pawl for said ratchet-wheel and means for disengaging said pawls from the ratchet-wheel, said means including at least one permanent magnet adapted to directly act onto and to disengage said pawls by magnetic attraction.

2. A timepiece according to claim 1, comprising at least one permanent magnet mounted for displacement substantially in the direction of the disengaging and engaging movement of said pawls.

3. A timepiece according to claim 1, comprising two springs carrying said pawls, the free ends of such springs being disposed near one single magnet.

4. A timepiece according to claim 1, comprising a friction coupling between said winding shaft and the wheels of the timepiece, and means for disengaging said friction transmission.

5. A timepiece according to claim 1, comprising a locking slide determining the axial position of the winding shaft, said means being operable by said locking slide.

6. A timepiece according to claim 1, wherein said ratchet-wheel is mounted on the shaft of the second wheel.

7. A timepiece according to claim 2, comprising a lever controllable by the winding shaft and carrying a permanent magnet.

8. A timepiece according to claim 3, comprising pole pieces of magnetizable material on opposite sides of the permanent magnet, air gaps being formed between said magnet and pole pieces respectively near said free ends of the springs.

9. A timepiece according to claim 4, wherein said winding shaft has a flexible portion adapted to be bent when said friction transmission is disengaged.

10. A timepiece according to claim 4, comprising a center-wheel having a slot, said winding shaft carrying a cylinder of resilient material adapted for engagement with said clot.

11. A timepiece according to claim 5, comprising a lever controllable by the winding shaft and carrying a permanent magnet, said lever being operable from said locking slide through a rocking lever having an arm adapted to lift said winding shaft for disengagement of said friction transmission.

References Cited UNITED STATES PATENTS 3,059,413 10/1962 Detwiler. 3,129,554 4/1964 Yasukawa 5885.5

FOREIGN PATENTS 422,750 l/1935 Great Britain.

RICHARD B. WILKINSON, Primary Examiner.

GEORGE H. MILLER, JR., Assistant Examiner.

US. Cl. X.R. 

